The France family, who owns NASCAR, has engaged investment bank Goldman Sachs to explore a sale of the sanctioning body, ESPN has confirmed.

Reuters first reported the potential for a sale, which has been rumored for more than a decade. Those rumors have increased over the past year amid NASCAR's struggles to attract fans, both in-person and on television. The three public companies that own tracks where NASCAR races take place have reported a combined attendance revenue decline of 54 percent over the past decade.

A spokesperson for NASCAR had no comment on the potential sale, which sources tell ESPN is not a foregone conclusion.

NASCAR does not comment on its ownership structure, but according to court documents in various lawsuits, it is co-owned by Jim France, the one surviving son of NASCAR founder Bill France Sr., and Lesa France Kennedy, the granddaughter of France Sr. and daughter of Bill France Jr.

"Our business is racing, that's what we're investing in," Jim France said after buying the Automobile Racing Club of America (ARCA) Series last month. "We've done it all of our lives, and we're going to continue to do it."

What would be included in any type of sale is unclear. Lesa spends much of her time focused on her role as CEO of International Speedway Corp., the publicly traded company that operates 12 racetracks. The France family, which includes Lesa's brother Brian, who serves as NASCAR's chairman and CEO, owns 74 percent of the company's stock.

NASCAR has also struggled with keeping sponsors, which are so integral to the sport. Gone in recent years are long-time brand supporters like Sprint, Home Depot, and UPS. Lowe's, which has sponsored Jimmie Johnson for 18 years, is leaving after this season. Monster Energy, which got a cheap $20 million deal to sponsor NASCAR's main Cup cars this year, has committed to another year, but will be a lame duck next season.

Possible bidders include Marcus Smith, president of Speedway Motorsports Inc. Insiders say Smith wants to make his own legacy in sports, separate from his father Bruton. While the Smiths had interest in buying the Carolina Panthers, the $2 billion-plus price tag was too much for them to become majority owners. Comcast is also bound to come up, not only because of its sponsorship of the Xfinity Series, but because the idea of a media company buying a racing series for content is fresh in minds after Formula One was purchased by Liberty Media.

One potential hurdle in negotiations could be that the NASCAR charter agreement -- NASCAR's version of a franchise -- with the teams runs only through 2020. The teams have the option to extend it through 2024, the end of the current 10-year television deal that is worth an average of $820 million each year. Any buyer likely would need assurances from the teams that they would continue to participate, and team owners could see this as their opportunity to obtain a bigger percentage of the television money. Teams currently get 25 percent through the race purse while NASCAR keeps 10 percent and the racetracks take in 65 percent.